A bug is thought to be an
emulation bug, when in fact, it may be a system bug.

CAUSE :

The bug may occur due to a
bug in a Kernel ROM function.

SOLUTION
:

Try using a different
version of the Kernel ROM (i.e. the KERNAL.ROM file, in the CCS64 installation
folder). Various bug-fixes have been made to various Kernel functions, in
later versions of the Kernel ROM. There are 3 Revisions of the Commodore 64
Kernel ROM.

Some games or demos,
however, rely on specific versions of the Kernel ROM, in order to work
properly.